It is well known to include a zoom lens in a photographic camera. A zoom lens is a variable focal length lens which can be adjusted continuously by movement of one or more groups of lens elements in the lens system. Typically, the lens system consists of positive and negative elements which undergo a change in separation to change the focal length of the zoom lens.
The prior art as exemplified by U.S. Pat. Nos. 2,782,683, issued Feb. 26, 1957, and 3,339,943, issued Sep. 3, 1968, suggests the use in a photographic camera of resistance means in the form of a potentiometer for providing various resistance values corresponding to respective positions of a zoom lens.